AB0863 SERUM ANTI-MITOCHONDRIAL-AMA, ANTI-TIF1GAMMA, ANTI-RO52 AUTOANTIBODIES CHARACTERIZE CANCER-ASSOCIATED DERMATOMYOSITIS
Authors: A. Ceribelli, A. Tonutti, N. Isailovic, M. De Santis, C. Selmi
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Cancer-associated myositis (CAM) remains a clinical challenge and established risk factors include older age, male sex, dermatomyositis (DM), and specific antibodies, including anti-TIF1gamma and -MJ/NXP2 [1]. However, a recent report suggests a lower risk of malignancy in -TIF1gamma positive patients with other concurrent autoantibodies (2,3), whereas the protective role against malignancy of antisynthetase or anti-Mi-2 antibodies is being questioned [1]. <h3>Objectives</h3> To describe the demographic, clinical, and serological characteristics of a cohort of patients with CAM in a specific autoantibody profile. <h3>Methods</h3> Retrospective cohort analysis on electronic clinical charts, autoantibody analysis by serum immunoprecipitation and ELISA. <h3>Results</h3> Malignancy was observed in 17/73 (23%) patients with IIM, in 13/17 (76%) within 5 years before or after IIM diagnosis and cancer relapse or progression in 7 cases; 2/17 were men with a median age of 56 years. Breast cancer was the most frequent, followed by lung, thyroid, ovarian, and lymphoma. Four patients died, three for cancer-related complications and one for severe refractory IIM. Muscle injury was observed in 13/17 (76%) while 2/17 experienced dysphagia. Skin lesions were present in 14/17 (82%) patients, while ILD (24%) and arthritis (18%) rarely occurred; no cases of myocardial involvement were described. Anti-Ro52 was the most common antibody (5/17 – 29%) in our cohort, detected as the only specificity in 2/5 cases. Anti-TIF1gamma was described in 4/17 (24%, one case with concurrent -Ro52), followed by antisynthetase (3 – 18%), -Mi-2 (2 – 12%), -MJ/NXP2, -SAE1, -SRP (1 each – 6%). Combined anti-E2/E3 PDH (AMA) and anti-Ro positivity was found in a patient who developed lymphoma and cholangiocarcinoma within two years from IIM. We compared CAM patients with (n=4) and without (n=13) serum anti-TIF1gamma (Table 1). Albeit not reaching statistical significance, dysphagia and skin disease were more frequently observed with anti-TIF1gamma, whereas arthritis, Raynaud's phenomenon, and capillaroscopy alterations were rarer in such group. Prevalence of early-stage cancer seemed more frequent with anti-TIF1gamma. 3/13 patients without anti-TIF1gamma died due to cancer-related causes; the only death observed in the TIF1gamma positive group was due to progressive IIM, and occurred in a patient with complete cancer remission. <h3>Conclusion</h3> We observed that DM remains the most common clinical subset of CAM, but other myositis phenotypes can be also observed. Anti-TIF1gamma remains the more prevalent autoantibody in CAM along with anti-Ro52. The role of AMA positivity may warrant further investigation, particularly in patients with seronegative CAM. <h3>References</h3> [1]Kardes S, et al. Best Pract Res Clin Rheumatol. 2022; [2]Fiorentino DF, et al. J Clin Invest. 2022; [3]Hosono Y, et al. Ann Rheum Dis. 2022. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> Angela Ceribelli: None declared, Antonio Tonutti: None declared, Natasa Isailovic: None declared, Maria De Santis: None declared, Carlo Selmi Speakers bureau: ABBVIE, AMGEN, ALFA-WASSERMANN, BIOGEN, ELI-LILLY, GALAPAGOS, JANSSEN, NOVARTIS, PFIZER, SOBI, Grant/research support from: ABBVIE, AMGEN, PFIZER.